The use of intra-aortic balloon assemblies for assisting the pumping action of the heart are well-known. Recently, research efforts have placed emphasis upon facilitating the insertion and placement of such balloon assemblies. One of the major objectives is to obtain reductions in balloon profile, i.e. outer diameter, in order to achieve the aforementioned results. Early efforts to achieve such results led to the technique of evacuating the balloon and wrapping the evacuated balloon about an elongated member substantially coaxial with the longitudinal axis of the balloon. This technique is disclosed in U.S. Pat. No. 3,939,820 issued on Feb. 24, 1976 to Grayzel et al. Another technique adopted to achieve substantially similar results utilizes a twistable, elongated stylet coaxial with the longitudinal axis of the balloon, one end of the balloon being rotatable relative to the opposing end, and being twisted about the stylus in order to reduce the balloon profile. This technique is disclosed in U.S. Pat. No. 4,261,339 issued Apr. 14, 1981 in the name of Hanson et al. A novel improvement on this technique is disclosed in application Ser. No. 253,680, filed Apr. 13, 1981, now U.S. Pat. No. 4,422,447, issued Dec. 27, 1983, in the name of the inventor of the present invention, and disclosing an intra-aortic balloon assembly having a stylet rotatable through a manually operable control knob arranged remote from the balloon, for wrapping the balloon.
The balloons of the above techniques which employ a flexible stylet may be introduced into the body through a percutaneous technique such as, for example, the Seldinger technique, wherein an introducer sheath is initially introduced into the body and the balloon is thereafter introduced into the body by insertion into and through said introducer sheath, which may then be either partially or totally removed after the balloon has been properly placed.
Still another technique for reducing the profile of the balloon but without either wrapping or twisting, is disclosed in U.S. Pat. No. 4,327,709 issued on May 4, 1982, to Hanson et al, and describing a technique in which the balloon is evacuated to form a flat tape-like cross-section with the stylet lying along the central axis thereof. The two halves of the balloon lying on either side of the stylus are folded over to form first and second longitudinal folds. The balloon is thereafter inserted into one end of an insertion sheath used in the performance of the Seldinger technique. This technique assumes that the balloon will form a sufficient number of additional longitudinal folds to enable its insertion into the insertion sheath.
Although all of the above-mentioned techniques tend to reduce the profile of the balloon, they nevertheless exhibit certain disadvantages. For example, the balloon assemblies which rely upon twisting techniques create a large number of folds to generate a non-uniform helical pattern which may damage the introducer sheath and/or the patient or the balloon itself, which is greatly stressed by such wrapping. The balloon assemblies adapted for folding and/or wrapping techniques also create a large number of folds, due to their geometry and thus all of the above techniques fall short of reaching a minimal outer profile and without introducing additional disadvantages. In addition thereto, none of the above techniques teach a pre-wrapped balloon, or a method or means for maintaining a pre-wrapped balloon in the fully and tightly wrapped state, until it is ready for insertion.